The car is essentially an open-air version of the new two-place Mini Coupe, but instead of a hard top styled after a backwards baseball cap, the Roadster wears a black fabric roof. Unlike the four-place Mini Convertible, the Roadster's roof is manually operated. Drivers simply twist a latch on the windshield frame and pull the roof back to its resting place behind the front seats. Instead of offering a pair of rear seats, the area behind the front seats is home to a shelf for carrying small items, and a 14-by-8-inch pass-through into the trunk.The Roadster is about the same length and width as the Coupe or Convertible models. Its windshield is sloped much more steeply than on other models -- 13 degrees more than the Convertible -- and it is tapered at the top to give a trapezoidal appearance from head-on. With the roof up, the Roadster has a bubble-shaped profile that reminds us of the original Audi TT. The sloping shape and narrower windshield make the Roadster slightly more aerodynamic than other Mini models. It also rides 0.75 inch lower than the Convertible.

As in the Coupe, the Roadster's chassis is stiffened by grace of extra bracing in the rear of the car and reinforced rocker panels. The car has an electrically operated rear spoiler, which opens at 50 mph and retracts when the car slows to 37 mph. It provides a claimed 88 pounds of downforce at high speeds, helping improve the car's stability. The use of a manual roof, however, lowers the Roadster's center of gravity, and the car is lighter than equivalent four-seat Convertible models. Curb weight ranges from 2635 pounds for the Cooper Roadster, to 2800 pounds for the Cooper S Roadster.